Jie Liu, Tao Guan, Peijing Zheng, Liyang Chen, Yang Yang, Baoyu Huai, Dan Li,Qing Chang, Lili Huang and Zhensheng Kang An Extracellular Zn-only Superoxide Dismutase from Puccinia Striiformis Confers Enhanced Resistance to Host-derived Oxidative Stress

An Extracellular Zn-only Superoxide Dismutase from Puccinia Striiformis Confers Enhanced Resistance to Host-derived Oxidative Stress

Jie Liu, Tao Guan, Peijing Zheng, Liyang Chen, Yang Yang, Baoyu Huai, Dan Li,Qing Chang, Lili Huang, Zhensheng Kang  

Environmental Microbiology 

DOI:10.1111/1462-2920.13451

Abstract: Accumulation of reactive oxygen species (ROS) following plant-pathogen interactions can trigger plant defence responses and directly damage pathogens. Thus, it is essential for pathogens to scavenge hostderived ROS to establish a parasitic  relationship.However, the mechanisms protecting pathogens from host-derived oxidative stress remain unclear. In this study, a superoxide dismutase (SOD) gene, PsSOD1, was cloned from a wheat—Puccinia striiformis f. Sp. tritici (Pst) interaction cDNA library. Transcripts of PsSOD1 were up-regulated in the early infection stage. Heterologous mutant complementation and biochemical characterization revealed that PsSOD1 encoded a Zn-only SOD. The predicted signal peptide was functional in an invertase-mutated yeast strain. Furthermore, immunoblot analysis of apoplastic proteins in Pst-infected wheat leaves and bimolecular fluorescence complementation suggested that PsSOD1 is a secreted protein that potentially forms a dimer during Pst infection. Overexpression of PsSOD1 enhanced Schizosaccharomyces pombe resistance to exogenous superoxide. Transient expression of PsSOD1 in Nicotiana benthamiana suppressed Bax-induced cell death. Knockdown of PsSOD1 using a host-induced gene silencing (HIGS) system reduced the virulence of Pst, which was associated with ROS accumulation in HIGS plants. These results suggest that PsSOD1 is an important pathogenicity factor that is secreted into the host-pathogen interface to contribute to Pst infection by scavenging host-derived ROS.